137 results about "Expectation–maximization algorithm" patented technology

The invention discloses a line intelligent planning and fault early warning method suitable for electric power engineering design, and relates to the technical field of electric power engineering. The method comprises the following steps: quantifying geographic information, geological conditions and construction cost into a continuous decision curved surface through spatial semantic segmentation and a cost curved surface model, and identifying a large-area low-cost region as a primary feasible region in combination with a dynamic clustering algorithm; a multi-dimensional decision index is constructed based on spatial features, geological stability and facility association data, fault regions such as terrain abrupt change or facility conflict are identified through real-time association coefficients, and an exception handling mechanism is triggered; and selecting a seed region with an optimal construction condition as an anchor point, constructing a joint probability model of spatial features and cost, and generating an optimal path considering feasibility probability and cost effectiveness in combination with an expectation maximization algorithm and a graph optimization technology. According to the invention, scientificity and economical efficiency of cable planning under complex geological conditions are improved, and key technical support is provided for intelligentization of electric power engineering.

The invention discloses a model training method and device, a storage medium and a computer program product, and relates to the technical field of artificial intelligence, and the method comprises the steps: obtaining a weight positive sample training set and a weight negative sample training set, the weight positive sample training set and the weight negative sample training set are obtained by labeling and screening a preset unlabeled sample set; based on a preset unbiased positive sample and unmarked sample learning algorithm, according to the weight positive sample training set and the weight negative sample training set, training to obtain a dichotomy model; iterating the dichotomy model through a loss function and a regular function corresponding to the dichotomy model based on a preset expectation maximization algorithm until the dichotomy model converges, and obtaining a converged dichotomy model; and taking the converged dichotomy model as a prediction model. The problems that an existing method is poor in universality and generalization and needs to label samples manually are solved, and the universality and generalization of model training are improved.

The invention discloses a multi-dimensional distribution offset adaptive threshold detection method and system, and the method comprises the steps: obtaining real-time data, extracting a multi-dimensional statistical feature, and obtaining a feature vector; based on historical normal data, using an expectation maximization algorithm to train a Gaussian mixture model, and determining parameters to obtain a normal distribution model; inputting the feature vector into the model, and calculating a probability value of the feature vector belonging to normal distribution as a first offset judgment index; based on the real-time data distribution of a plurality of detection objects in the same group, the distribution difference of any two objects is calculated by using a Wasserstein distance, and the similarity between the objects is obtained; and constructing a similarity network and calculating connectivity as a second offset judgment index. Setting a fixed-length sliding window, dynamically updating two indexes in the window, and obtaining a first self-adaptive threshold value and a second self-adaptive threshold value; and when any index is lower than a corresponding threshold value, determining distribution offset and giving an alarm, and updating model parameters in real time by using an incremental expectation maximization algorithm. According to the invention, accurate detection and intelligent analysis of data distribution offset are realized.

The invention provides a communication auxiliary sensing system and method based on an intelligent super surface (RIS). The communication auxiliary sensing system comprises a multi-antenna base station, a multi-user terminal and an active RIS. According to the system, an uplink pilot frequency and a data signal are jointly utilized, an expectation maximization (EM) algorithm is adopted to iteratively recover equivalent channel state information (CSI), and a Cramer-Rao bound (CRB) of sensing performance is deduced. Combined optimization of user precoding and RIS reflection coefficients is innovatively proposed under the uncertainty of CSI, so as to minimize CRB and guarantee user communication rate at the same time. An original problem is converted into a processable form by establishing a traversal MIMO spectrum efficiency compact lower bound, and efficient optimization is realized by combining a WMMSE method with a block coordinate descent (BCD) frame. According to the scheme, the sensing precision and the spectrum efficiency are remarkably improved, the method is suitable for an active RIS-assisted MU-MIMO network, and the technology can also be expanded to a traditional RIS-free system.

The invention discloses a deception jamming signal identification and interference source positioning method and system, and belongs to the technical field of signal identification and interference source positioning, and the method comprises the steps: receiving intermediate frequency receiving signals of a global satellite navigation system, including a real satellite signal, a forwarding deception jamming signal, a multipath signal and a noise signal; performing multi-component parameter estimation based on a space alternating generalized expectation maximization algorithm to obtain a parameter set comprising time delay, Doppler frequency shift and complex amplitude; according to consistency detection of receiver clock differences and Doppler frequency shift information of a plurality of adjacent base stations, identifying deception jamming components and real signal components from the parameter set; and determining the position of an interference source by adopting a delay inequality positioning algorithm based on the arrival delay inequality of the deception interference component among the plurality of adjacent base stations. According to the method, the GNSS signal characteristics are utilized, space-power time-frequency joint detection is realized with low complexity under the condition of not needing extra hardware cost, and the performance of deception jamming detection in practical application is improved.

The invention belongs to the technical field of wireless communication, and particularly relates to a positioning method based on low-orbit satellite opportunity signal Doppler measurement. The method solves the Doppler measurement positioning problem based on low orbit (LEO) satellite opportunity signals under the condition that GNSS signals are limited or unavailable. A positioning process is modeled as a non-linear state space framework, a joint estimation scheme combining a cubic Kalman smoother and an expectation maximization algorithm is provided, efficient estimation of a terminal position and Doppler frequency shift is realized, and noise covariance is adaptively optimized at the same time. The method provided by the invention theoretically ensures the optimal performance in statistical significance. A simulation result shows that compared with a traditional nonlinear least square method, the scheme provided by the invention can remarkably improve the positioning precision, and the calculation overhead is kept reasonable and balanced.

The invention relates to the technical field of voice recognition, and discloses a voiceprint model training method, a user identity detection method and device, and an intelligent household electrical appliance, and the voiceprint model training method comprises the steps: carrying out the preprocessing of a voice signal, and extracting a mixed feature vector containing a static frequency spectrum feature and a time difference feature; training a Gaussian mixture model to be converged by adopting an expectation maximization algorithm based on the mixed feature vector; and outputting the special voiceprint model of the speaker. The voiceprint model obtained by training through the training method is used for user identity detection, and high robustness, high real-time performance and high accuracy of voiceprint recognition in a complex noise environment are achieved.

The invention discloses a natural electric field-electric field joint detection and inversion method based on GMM prior, and relates to the technical field of tunnel engineering geological detection, and the method comprises the steps: obtaining the resistivity and natural potential observed in a to-be-inverted region; an equivalent body source of a natural potential is parameterized into a body source vector on a grid unit, weighted L1 sparse regular constraint is introduced into the body source vector, a GMM prior model is used as underground electrical structure prior shared across physics fields, and a multi-task joint inversion objective function of a shared underground electrical structure label is established; and performing inversion iteration by adopting maximum posteriori, updating parameters of the GMM prior model and the underground electrical structure label by adopting an expectation maximization algorithm until an end condition is met, and obtaining a joint inversion imaging result of the tunnel water-rich anomalous body. The advantages of a multi-source electrical method are fused, underground electrical structure priori is introduced, Bayesian uncertainty analysis is combined, and high-resolution and high-reliability recognition of the water-rich anomalous body in front of the tunnel is achieved.

The invention discloses a personalized picture book intelligent recommendation system based on combination of innovative sentence vectors and a hidden semi-Markov model, which belongs to the technical field of education and comprises a data acquisition module, a sentence vector generation module, an interest tracking module, a recommendation generation module, the innovative sentence vectors, the hidden semi-Markov model and an expectation maximization (EM) algorithm. According to the method, an efficient and accurate personalized picture book recommendation system is successfully constructed through deep fusion of the innovative sentence vectors and the HSMM, the problem of interest drifting of students in the reading process is effectively solved, the innovative sentence vectors can comprehensively capture deep semantics and emotional tendencies of reading texts of the students, and the interestingness of the students is improved. A rich and multi-dimensional data basis is provided for interest analysis, the HSMM model allows the students to stay for different time durations in different potential interest states, the heterogeneity of the interest duration of the students is accurately described, and dynamic tracking of interest changes of the students is achieved.

The invention discloses a method and a system for measuring a time average velocity field of a combustion chamber of a scramjet engine, and belongs to the technical field of average velocity field measurement. The method comprises the following steps: establishing a measurement system, matching the number of exposure frames of a high-speed camera with the number of cavities of a laser, collecting a time sequence image for pre-processing, obtaining the pre-processed time sequence image, dividing the time sequence image into grid slices for cross-correlation calculation, and obtaining a time sequence speed according to a space and pixel conversion coefficient; constructing a velocity model according to a Gaussian mixture model algorithm, and obtaining a probability matrix of a data point belonging to a correct velocity vector according to an expectation maximization algorithm; and calculating to obtain a time average velocity field according to the correct velocity vector and the error velocity vector judgment condition. The method effectively improves the efficiency and accuracy of measuring the distribution of the time average velocity field, and can be used for measuring the time average velocity field.

The invention relates to the technical field of satellite navigation positioning, in particular to a Beidou robust Kalman filtering positioning method based on a non-Gaussian noise model. According to the method, non-Gaussian noise generated by shielding and a multipath effect in Beidou positioning is accurately represented by constructing a Gaussian mixture model and a student t distribution model, model parameters are updated online by an expectation maximization algorithm, and the problem that a traditional Gaussian hypothesis model cannot adapt to noise statistical characteristics is solved; the non-Gaussian noise model is fused with robust filtering, a self-adaptive robust weight matrix is constructed through a Huber cost function, an IGGIII scheme or noise probability density, an observation covariance matrix is dynamically adjusted, the influence of abnormal observation values is suppressed, the defects that classical robust filtering lacks noise modeling and weight adjustment fails under continuous strong interference are overcome, and the robustness of the robust filtering is improved. And meanwhile, the problem of complex particle filtering calculation is avoided.

The invention discloses an Internet of Things anomaly detection method and system based on quaternion state space diffusion enhancement, and belongs to the technical field of network security and artificial intelligence. The method comprises the following steps: mapping a flow time sequence feature into a quaternion tensor to maintain an internal coupling relationship of a multi-dimensional feature; a double-flow encoder is designed, a quaternion selective state space model is adopted to extract continuous fluid features, and a dynamic hypergraph neural network is adopted to model discrete protocol features; carrying out self-supervised pre-training on a resistance pseudo-anomaly sample by utilizing potential diffusion model generation, and optimizing characterization by combining quaternion cepstrum distance loss; the injected learnable prompt vector is optimized in the small sample fine tuning stage, and a category prototype is corrected by using a semi-supervised expectation maximization algorithm; and calculating a sample anomaly score based on an energy model to realize known attack classification and unknown anomaly judgment. According to the method, the generalization ability of the model under the small sample condition and the unknown threat detection ability are remarkably improved.

The invention provides a cluster-based control system data statistics method and system. The method comprises the following steps: determining a multi-dimensional time sequence state data core object of a control system; starting from any unaccessed core object, forming an initial data cluster, fitting a Gaussian mixture model by using an expectation maximization algorithm, and extracting a parameter set of the Gaussian mixture model as statistical characteristics of the cluster; iteratively calculating the Bhattacharyya distance between the Gaussian mixture models of any two data clusters, and when the distance is smaller than a preset merging threshold value, re-fitting the Gaussian mixture model for the merged new clusters until no cluster can be merged; in any data cluster, cluster generation and combination are carried out again; data points which do not belong to any cluster are regarded as noise points, a noise point set of the region is regarded as a new data set according to the space-time density, and cluster generation, merging and splitting steps are executed on the new data set to generate a new cluster; and outputting the Gaussian mixture model parameter set of all the current data clusters as a statistical result of the current working condition of the control system.

The invention discloses a hybrid antenna array direction of arrival estimation method based on noise marginalization SBL. The method comprises the following steps: initializing system parameters and a sampling grid set; establishing a hybrid antenna array receiving signal model, and initializing a hybrid beam forming matrix into a block diagonal matrix meeting constant modulus constraint; constructing a hierarchical probability model under a Bayesian framework, and introducing a noise precision parameter into signal prior; integral operation is carried out on the noise precision parameter, so that the signal posterior distribution is converted into student t distribution; an objective function is constructed, an expectation maximization algorithm is adopted to iteratively update a signal energy spectrum, and the process does not involve noise parameter estimation; an alternating iteration strategy is adopted, the signal energy is fixedly updated through inner circulation, and optimization is performed through a gradient descent method after outer circulation is fixed; after convergence, constructing a target function of off-grid estimation by reconstructing a covariance matrix; and searching the off-grid direction of the maximized objective function near a spectrum peak to obtain a final DOA estimation value.

The invention discloses a frequency domain adaptive clutter suppression method and system for a dual-polarization weather radar, and relates to the technical field of weather radar processing. According to the invention, pulse-level quality control and ground feature identification marking are carried out on radar original echoes; calculating power spectrums of the marking units, performing dynamic noise measurement and data quality grading, and screening out effective processing units; constructing a Gaussian mixture model of a power spectrum of an effective unit, and iteratively estimating model parameters through an expectation maximization algorithm to realize complete separation of a ground feature spectrum and a meteorological spectrum in a frequency domain; inverting single-channel parameters based on the separated meteorological spectrum; a cooperative spectrum separation strategy is adopted for horizontal and vertical polarization channels, and dual-polarization parameters such as differential reflectivity, correlation coefficients and differential phases are inverted based on the filtered dual-channel signals; according to the invention, high-precision separation of clutters and meteorological echoes is realized, the loss of meteorological signals is significantly reduced while ground features are effectively suppressed, and the accuracy and reliability of dual-polarization parameter inversion are improved.

The invention relates to the technical field of target tracking, and discloses an LSTM-KF hybrid tracking method based on parameter adaptation, which comprises the following steps: acquiring target position measurement data of a moving target, and extracting dual-channel characteristics of the target position measurement data through a sliding window; inputting the dual-channel features into a pre-trained dual-channel LSTM network to obtain a target position prediction result and a target speed prediction result; analyzing target motion characteristics based on a prediction result, selecting a corresponding dynamic model according to a motion mode, and performing target state estimation on the dynamic model through a Kalman filter; and finally, optimizing noise parameters of the Kalman filter by adopting an expectation maximization algorithm, carrying out weighted fusion on a prediction result of the dual-channel LSTM network and a target state estimation result, and outputting a final target state. According to the invention, high-precision and high-robustness target tracking in a complex environment is realized.

The invention discloses an intelligent flood forecasting method for coupling error correction and joint modeling, and relates to a deep learning and uncertainty modeling technology. At the input end, constructing a future random rainfall scene through hourly dynamic normal disturbance; the method comprises the following steps: at a model end, introducing a multi-structure and multi-objective function combination based on Kolmogorov-Arnold Networks and Transform, and forming a multi-member ensemble forecast; at an error end, a probabilistic modeling method based on a numerable asymmetric Laplacian mixed density network is provided, and fine error correction is realized; a Vine copula function is adopted to construct high-dimensional joint distribution, and a Bayesian model averaging and expectation maximization algorithm is combined to realize weighted fusion of multi-member posterior results; according to the method, uncertainty in flood forecasting can be comprehensively described, the stability and adaptability of a forecasting system are improved, and the method is suitable for a basin-level real-time flood ensemble forecasting scene.

The invention discloses a lithium ion battery health state and residual service life prediction method and system. The method comprises the steps of collecting multi-dimensional parameter data of a lithium ion battery in a charging and discharging process; preprocessing the multi-dimensional parameter data, screening out key features closely related to the health state of the battery by using a correlation analysis method, and establishing fusion feature data; performing statistical modeling on data distribution by adopting a Gaussian mixture model based on the fused feature data, and optimizing model parameters through an expectation maximization algorithm so as to accurately predict the health state of the lithium ion battery; and constructing a training set and a test set for residual service life prediction to train and predict the residual service life model, setting feature factor fusion with high correlation according to different battery data, and performing model training to obtain a prediction result of the residual service life. According to the invention, the accuracy and robustness of lithium ion battery prediction can be improved, and more reliable data support is provided for a battery management system, so that the service life of the battery is effectively prolonged.

The invention discloses a radar interference effect evaluation method based on a constraint learning dynamic Bayesian network, is applied to the field of radar interference evaluation, and aims at solving the problem that the accuracy of interference effect evaluation is reduced due to radar detection data missing in a complex electromagnetic environment. Meanwhile, parameter constraints of five types of evaluation indexes and interference effect grades are defined; secondly, constructing a constraint learning dynamic Bayesian network, and learning a conditional probability and a transition probability under a data missing condition; then, proposing a prior constraint expectation maximization algorithm, converting parameter learning into an optimization problem with constraint by combining convex optimization, and overcoming the defects of a traditional expectation maximization algorithm; secondly, a cloud model is introduced to quantify discrete probability distribution into a continuous interference degree value; finally, simulation shows that the method can effectively improve parameter learning stability and evaluation accuracy under the conditions of suppressing and deception jamming and single index deficiency, and provides a reliable scheme for radar jamming effect evaluation in a complex environment.

The invention discloses an ultrasonic cross-metal channel estimation method based on improved block sparse Bayesian learning, and belongs to the field of ultrasonic cross-metal communication channel estimation. Constructing a pilot signal relationship between the receiving end and the transmitting end on the two sides of the metal wall; dividing a to-be-estimated metal channel impulse response into zero-value blocks or non-zero blocks of block sparse Bayesian according to whether the to-be-estimated metal channel impulse response is zero or not; the method comprises the following steps: iteratively updating hyper-parameters a, b, Bi and lambda of a non-zero block by adopting an expectation maximization algorithm, realizing structured sparse learning, calculating a maximum posteriori estimation result by utilizing a final hyper-parameter of the non-zero block, and taking the maximum posteriori estimation result as an estimation value of ultrasonic cross-metal channel pulse response. According to the method, a block sparse Bayesian learning algorithm is improved by utilizing the characteristics of metal channel pulse response, and compared with an original algorithm, the accuracy of channel estimation in a low signal-to-noise ratio environment is improved.

The invention discloses a multi-dimensional night urination behavior monitoring system based on rhythm features, and relates to the technical field of biomedical signal processing, and the system specifically comprises a data acquisition module, a rhythm feature extraction module, a urine volume dynamics modeling module, a clustering monitoring module and a real-time feedback module; collecting individual data in real time through IoT equipment and preprocessing the individual data; calculating a nocturnal urination frequency index, a nocturnal urination time concentration ratio, a urination interval rhythm variation coefficient and a deviation index based on the individual data, and performing rhythm feature extraction; performing quadratic polynomial least square fitting on the night accumulated urine volume, and calculating a urine volume acceleration index by using an obtained second derivative to quantify a urine volume generation trend; the method comprises the following steps: constructing and preprocessing a night urine multi-dimensional digital phenotypic vector matrix, fitting a Gaussian mixture model based on an expectation maximization algorithm of a Bayesian information criterion, automatically mapping individuals into four types of subtypes according to cluster center features, and outputting individual subtype labels and confidence coefficients; and obtaining a comprehensive risk score through normalized risk assessment.

The application provides a spectrum overlapping peak decomposition method, device, equipment and medium, the method comprises: to X ray fluorescence spectrum, through the global search of particle swarm optimization algorithm APU-PSO with adaptive parameter updating strategy, obtain the initial parameter of Gaussian mixture model GMM, the initial parameter includes the peak position, variance and the weight of each sub-peak in the overlapping peak Gaussian characteristic peak, and the GMM models the overlapping peak as the superposition of multiple Gaussian characteristic peaks; based on the initial parameter, the parameters of GMM are iteratively optimized through expectation maximization algorithm EM, the optimal parameters of each Gaussian characteristic peak are obtained, and then the optimal parameter set containing the peak position, variance and the weight of each sub-peak in the total peak area of each Gaussian characteristic peak is determined. The application can effectively improve the accuracy and reliability of X ray fluorescence spectrum overlapping peak decomposition.

The application discloses a lithium battery residual life prediction method based on a multi-stage Wiener process, relates to the technical field of lithium batteries, and establishes a lithium battery degradation model based on a Wiener process; a degradation state and model parameters are adaptively estimated based on an expectation maximization EM algorithm and a Kalman smoothing method; in order to predict the residual life at the current moment, the degradation state at a change point is considered to be unknown, a probability density function of the residual life is solved, and an estimated value of the residual life is obtained. The application adopts the above lithium battery residual life prediction method based on the multi-stage Wiener process, establishes a multi-stage Wiener process degradation model based on measurement error, solves and simplifies the probability density function of the residual life, and improves the accuracy of lithium battery residual life prediction.

The application provides a continuous casting crystallizer vibration device residual life prediction method, comprising the following steps: S1. obtaining the vibration deflection of the continuous casting crystallizer vibration device to be measured and taking the vibration deflection as degradation data; S2. constructing a continuous casting crystallizer vibration device degradation model; S3. determining a drift coefficient in the degradation model and a parameter vector of the drift coefficient based on a nonlinear function regression algorithm; S4. estimating the prior parameters of the continuous casting crystallizer vibration device degradation model based on an expectation maximization (EM) algorithm and determining optimal prior parameters θ; S5. constructing a residual life probability density model, substituting the prior parameters into the residual life probability density model to calculate residual life probability values, and taking the residual life corresponding to the maximum probability value as the final prediction value of the residual life of the continuous casting crystallizer vibration device; only the degradation data of the continuous casting crystallizer vibration device to be measured is needed to accurately predict the residual life of the vibration device.

The invention discloses a two-stage adaptive numerical distribution reconstruction method based on local differential privacy. And the terminal equipment applies a local differential privacy perturbation mechanism to the held numerical private data to generate perturbation data and sends the perturbation data to the aggregation server. After an aggregation server collects data, first-stage estimation is executed firstly, and initial smooth distribution with low variance characteristics is generated based on an EMS algorithm to serve as a guide map; then, a non-uniform self-adaptive bucket dividing strategy is constructed according to cumulative distribution characteristics of initial distribution, and equal probability interval division is achieved; and finally, second-stage estimation is executed, re-statistics is carried out on noise data based on a self-adaptive bucket dividing strategy, accurate reconstruction is carried out by applying an expectation maximization algorithm with space kernel smoothing, and weighted updating is carried out on threshold-controlled space smoothing by utilizing a kernel function based on a bucket center physical distance. According to the method, the problem of over-fitting of discretization deviation of uniform bucket division and an expectation maximization algorithm in a local differential privacy high-noise environment is effectively solved through a two-stage strategy, and the accuracy and robustness of value distribution estimation are remarkably improved.

The invention relates to the technical field of power systems, in particular to a wind-light and load typical scene optimization method. The method comprises the following steps: establishing a mathematical model of core equipment in the multi-energy coupling system; on the basis of the mathematical model, an improved Gaussian mixture model and an improved expectation maximization algorithm are adopted, and a typical scene set with probability distribution fitting reality is generated in combination with space-time correlation characteristics of wind and light output and loads; the method comprises the following steps of: constructing an optimal scheduling model containing multi-energy supply and demand balance constraints by taking system total cost minimization as a target and combining an operation boundary condition and a typical scene set of core equipment, and solving the optimal scheduling model after performing linearization processing on the optimal scheduling model to obtain a flexibility adjustment scheme of the multi-energy coupling system. According to the method, the influence of multiple uncertain factors on the system regulation capability can be comprehensively reflected, the modeling precision of the probability distribution of uncertain variables such as wind, light, load and the like is improved, and the accuracy of the flexibility evaluation of the power system and the rationality of resource allocation are improved.

This application relates to the field of computer vision technology and discloses an anomaly event detection method, apparatus, device, storage medium, and product. The method includes: based on a deep neural network encoder, mapping video event samples to a feature space to obtain video features and initial clusters; based on the expectation-maximization algorithm, obtaining optimized clusters, an updated deep neural network encoder, and a prior distribution based on the video features and initial clusters; and detecting anomaly events in the video based on the optimized clusters, the updated deep neural network encoder, and the prior distribution. This application, through the expectation-maximization algorithm, can iteratively optimize the initial clusters and deep neural network encoder based on video features and initial clusters, and learn the prior distribution, improving cluster accuracy and better adapting to data characteristics. This results in more accurate extraction of video features, better differentiation between normal and abnormal events during anomaly detection, and improved detection accuracy.

The present application relates to a method for optimizing energy consumption of an electric-thermal integrated energy system with reduced loss, comprising: obtaining energy consumption data of the electric-thermal integrated energy system; processing the obtained energy consumption data, classifying it according to energy consumption regions, and dividing time periods; analyzing the energy consumption data of different regions respectively, obtaining consumption sources; optimizing the energy consumption of different regions respectively, generating improvement suggestions for the consumption sources; implementing loss reduction measures, and analyzing and comparing the loss reduction effects, recording the effective loss reduction measures for popularization and use. The present application also discloses an energy consumption optimization system. The present application obtains energy consumption data of different regions and different time intervals, monitors energy consumption abnormal nodes in real time; uses a normal distribution probability model of an expectation maximization algorithm to calculate the optimal energy consumption data distribution, generates improvement suggestions for the consumption sources, and optimizes energy consumption.

The invention discloses a low signal-to-noise ratio ADS-B (Automatic Dependent Surveillance-Broadcast) signal coherent receiving method based on an expectation maximization algorithm, which belongs to the technical field of coherent receiving methods, and comprises the following steps of: realizing accurate synchronization of ADS-B signals through energy accumulation and matched filtering, and then estimating and compensating frequency offset and phase offset through the expectation maximization algorithm, and finally, decoding and brute force error correction are carried out. According to the method, information bits behind a leading head are fully considered, the value probability of each bit is analyzed, and actually transmitted data information is taken as a hidden variable, so that the estimation precision of frequency offset and phase offset is greatly improved, the sensitivity index of a satellite-based ADS-B receiver can be effectively improved, the sensitivity of the receiver can reach-102dBm under 90% of correct decoding probability, and the accuracy of the receiver is improved. And meanwhile, the processing delay of the frequency phase offset estimation is less than 50 us, so that the coherent receiving method with limited resources can be used on the small cubesat more easily.

The application discloses an Internet of Things anomaly detection method and system based on quaternion state space diffusion enhancement, and belongs to the technical field of network security and artificial intelligence. The method comprises the following steps: mapping traffic time sequence features into a quaternion tensor to maintain the internal coupling relationship of multi-dimensional features; designing a double-flow encoder, extracting continuous flow features by using a quaternion selective state space model, and modeling discrete protocol features by using a dynamic hypergraph neural network; generating an adversarial pseudo-anomaly sample by using a latent diffusion model to perform self-supervised pre-training, and combining a quaternion cepstrum distance loss to optimize the representation; optimizing the injected learnable prompt vector in the small sample fine-tuning stage, and correcting the class prototype by using a semi-supervised expectation maximization algorithm; calculating sample anomaly scores based on an energy model to realize known attack classification and unknown anomaly determination. The application significantly improves the generalization ability of the model under the condition of small samples and the detection ability of unknown threats.